Comparison of the effects of ultraviolet and gamma rays on arsenic tolerance in the bioleaching process

One of the factors which can kill or decrease the viability of bioleaching bacteria is the creation of toxicity due to the process of metal release from mine stone. This toxicity is partly due to the presence of arsenic in mine stone. In the present study mutagenesis method was used to improve the bioleaching process performance by using UV and gamma rays. The influence of radiations (UV& gamma rays) on growth and death of Thiobacillus ferrooxidans bacteria were investigated at different time exposures. Afterwards, a defined concentration of arsenic salt (NaAsO5) was added to the remaining bacteria until mutant bacteria with arsenic resistance were separated. The results showed that irradiation time of 180 second and 120 minute of gamma and UV rays, causes the number of bacteria to increase by 20% and 45%, respectively.